Tears, hugs and celebrations Friday marked the end of a 20-year mission to Saturn for the spacecraft Cassini.

In mission control at NASA's Jet Propulsion Laboratory in Pasadena, California, Cassini program manager Earl Maize's voice was heard loud and clear: "The signal from the spacecraft is gone, and within the next 45 seconds, so will be the spacecraft."

"This morning, a lone explorer, a machine made by humankind, finished its mission 900 million miles away. The nearest observer wouldn't even know until 84 minutes later that Cassini was gone. To the very end, the spacecraft did everything we asked," he said.

Launched in 1997, Cassini's trip to Saturn took seven years.

"When I look back at the Cassini mission, I see a mission that was running a 13-year marathon of scientific discovery, and this last orbit was just the last lap," Cassini project scientist Linda Spilker said.

This Sept. 13, 2017, image made available by NASA on Sept. 15, 2017, shows the northern hemisphere of Saturn as seen from the Cassini spacecraft on its descent toward the planet.

Saturn and its moons

Cassini has been exploring Saturn and some of its moons, making discoveries along the way.

"The discoveries that Cassini has made over the last 13 years in orbit have rewritten the textbooks of Saturn, have discovered worlds that could be habitable and have guaranteed that we'll return to that ringed world," Jet Propulsion Laboratory Director Michael Watkins said.

Cassini discovered ocean worlds on the Saturn's moons Titan and Enceladus. It also detected strong evidence of hydrothermal vents at the base of Enceladus' ocean.

These discoveries prompted the decision to destroy Cassini as it ran out of fuel, so there would be no risk of contaminating these moons with bacteria from Earth.

In its last hours, Cassini took final images, including Enceladus setting behind Saturn; Saturn's rings; Titan's lakes and seas; and an infrared view of Saturn.

As Cassini plunged into Saturn, its sensors experienced the first taste of the planet's atmosphere, sending critical information to Earth until it disintegrated.

"It just really tells us about how Saturn formed and the processes going on and really how all the planetary bodies in our solar system have formed," said Nora Alonge, Cassini project science and system engineer.

Engineer Mar Vaquero monitors the status of NASA's Cassini spacecraft as it enters the atmosphere of Saturn, in mission control at NASA's Jet Propulsion Laboratory, Sept. 15, 2017, in Pasadena, Calif.

Bittersweet moments

The final moments of the spacecraft's journey were bittersweet for Alonge, who has been working on the Cassini mission for more than a decade.

"I'm feeling so many emotions. I'm very proud and I'm honored to be part of such an amazing mission, such a fruitful scientific mission, an engineering feat for a robust spacecraft that has lasted for so long, and of course I'm sad," she said. "I feel like I've lost a friend. We've been talking to Cassini for years. We check on the health and safety. It talks back to us and gives us data. That'll be missed. It'll be a big change for many of us."

"This, this has truly been beyond my wildest dreams," said Julie Webster, Cassini's spacecraft operations manager. She was with this mission from the time Cassini was built.

The members of the Cassini mission team said the end of the spacecraft was picture perfect.

"We found the best possible solution to get scientific data that would have been too risky to take at any other time by diving between the planet and the rings. We're going into a region we could have never explored before. Cassini is becoming now a part of Saturn, and it's the perfect ending point," Alonge said.

IN PHOTOS:Cassini's Amazing Pictures of Saturn, Rings & Moons

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Cassini's Amazing Photos of Saturn, Rings & Moons

Scientists said the end of Cassini also marked the beginning of other planetary explorations and more discoveries as scientists continue to analyze the unprecedented data on Saturn collected by Cassini.